Lecture 11

Question 1

Roles of the vestibular system

Answer 1

• maintain equilibrium (we unstable as bipedal animals)
• maintain gaze stability (so world doesn’t appear to bounce as we walk)

Question 2

important senses for balance

Answer 2

• Vestibular system
• Visual system
• Proprioception (awareness of where you are in space)
• auditory

all converge in brain stem

Question 3

Nystagmus

Answer 3

Reflex eye movement
Spinning chair example (slowly towards left until can’t go any further then quickly to the right)

this vestibular response can be overridden if given something to focus on

Question 4

vestibular anatomy

Answer 4

Three semi circular canals
Two otolithic organs

has membranous and bony labrynth

Fluids in vestibular system are continuous with cochlea fluids

Question 5

role of semicircular canals (overview)

Answer 5

transduce (detect) rotational acceleration (spinning)

Question 6

What are the two otolithic organs and their roles

Answer 6

Utricle
- primarily horizontal linear acceleration (forward, back, right left)
- close to semicircular canals

Saccule
- primarily vertical acceleration (up and down) *like SACk of potatoes falling
- close to cochlea

Question 7

role of otolithtic organs (overview)

Answer 7

transduce (detect ) gravity and linear acceleration (up, down, forwards, back)

the organs are very heavy, helps detect gravity

Question 8

The three semicircular canals

Answer 8

Anterior canal
Posterior canal (joined to anterior canal via the common crus)
Lateral canal (horizontal) (not joined to either)

Question 9

vestibular nerve innervation

Answer 9

SUPERIOR VESTIBULAR NERVE
- lateral SCC, anterior SCC and utricle

INFERIOR VESTIBULAR NERVE
- posterior SCC and saccule

IVN splits into singular nerve too –> posterior SCC

Question 10

Horizontal/lateral SCC orientation and role

Answer 10

Lateral, towards middle ear
Detects left and right head movements (move right and right H SCC is excited and left is inhibited)

ON THE SAME PLANE (matched)

Question 11

anterior and posterior SCC

Answer 11

same plane as each other

push pull system

(mix between nod and shake)

Question 12

utricle plane and saccule plane

Answer 12

utricle tilted up by 30 degrees
saccule tilted down 60 degrees

90 degrees away from eachother

Question 13

How are the posterior and anterior scc joined

Answer 13

The common crus